Generally, an eyeglass lens such as a progressive multi-focal lens, for example, is provided with print marks or hidden marks as a reference marker that are used in mounting a jig, which is used in processing the eyeglass lens, on the eyeglass lens.
Conventionally, the following Patent documents 1 to 8, for example, disclose a jig mounting apparatus that detects an identification marker such as the hidden marks by a detection optical system, determines an mounting point based on the identification marker detected by the detection optical system to position the jig used in processing the eyeglass lens at the mounting point, and mounts the jig on the eyeglass lens.    Patent document 1: Japanese Utility Model Registration No. 3077054 gazette    Patent document 2: Germany Patent Publication No. 3829488 gazette A1    Patent document 3: The United States Patent Publication No. 2003-15649 gazette    Patent document 4: Japanese Patent Laid-Open No. 2002-296144 gazette    Patent document 5: Japanese Patent Laid-Open No. 2000-19058 gazette    Patent document 6: Japanese Patent Laid-Open No. 2002-139713 gazette    Patent document 7: Japanese Patent Laid-Open No. 2002-1638 gazette    Patent document 8: European Patent Registration No. 856728 gazette B1
The jig mounting apparatus disclosed in each of these documents binarizes an image which is obtained by imaging the identification markers formed by printing, engraving or the like on the eyeglass lens, to detect the identification markers.
However, there were cases where each jig mounting apparatus doubly images the identification markers such as the hidden marks and print marks or the like, and in such a case, there was a problem that it was difficult to discriminate which of the doubly imaged identification markers should be used as a reference to determine the mounting point.
The present invention has been created in view of the above-described problem of the prior art, and an object of the present invention is to provide a jig mounting apparatus that is capable of detecting hidden marks as identification markers more accurately and capable of surely determining an mounting point, and thus capable of surely attaching a jig on an eyeglass lens with good accuracy.